我尝试用这种方法在画布上绘制位图URI， 尝试这个：
（下面代码给出解释）
private void drawBitmapUriOnCanvas(Uri selectedImage) {
if (selectedImage != null) {
BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inJustDecodeBounds = true;
try {
BitmapFactory.decodeStream(getContentResolver().openInputStream(
selectedImage), null, bmpFactoryOptions);
bmpFactoryOptions.inSampleSize = 2;
bmpFactoryOptions.inJustDecodeBounds = false;
Bitmap bmp = BitmapFactory
.decodeStream(getContentResolver().openInputStream(
selectedImage), null, bmpFactoryOptions);
Bitmap alteredBitmap;
if (bmp != null) {
if (getDeviceRam(this) <= 1024) {
bmp = getResizedBitmap(bmp, displayWidth);
}
bmp = checkAndRotateBitmap(bmp);
alteredBitmap = Bitmap.createBitmap(bmp.getWidth(), bmp
.getHeight(), bmp.getConfig());
Canvas canvas = new Canvas(alteredBitmap);
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setStrokeWidth(5);
paint.setAntiAlias(true);
Matrix matrix = new Matrix();
canvas.drawBitmap(bmp, matrix, paint);
(now alteredBitmap is processed bitmap and you can use it)
}
} catch (FileNotFoundException e) {
Toast.makeText(this, "Error reading Image Metadata", Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
}
其他包含的方法：
public static long getDeviceRam(Context context) {
ActivityManager actManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
ActivityManager.MemoryInfo memInfo = new ActivityManager.MemoryInfo();
actManager.getMemoryInfo(memInfo);
long totalMemory = memInfo.totalMem;
long fileSizeInKB = totalMemory / 1024;
// Convert the KB to MegaBytes (1 MB = 1024 KBytes)
return fileSizeInKB / 1024;
}
public static Bitmap getResizedBitmap(Bitmap image, int maxSize) {
int width = image.getWidth();
int height = image.getHeight();
float bitmapRatio = (float) width / (float) height;
if (bitmapRatio > 1) {
width = maxSize;
height = (int) (width / bitmapRatio);
} else {
height = maxSize;
width = (int) (height * bitmapRatio);
}
return Bitmap.createScaledBitmap(image, width, height, true);
}
在这里，首先我使用解码图像 uriBitmapFactory，然后我检查了设备内存，它是 1GB，然后我调整位图的大小，否则原始位图就可以用于下一步，
接下来只是在画布上绘制位图，您将得到alteredBitmap将是处理后的位图，使用起来会很方便。
如果这不起作用，那么还有另一个选项可以完成您的要求，如下所示：
Bitmap bitmap = getBitmapFromGallery(selectedImage.getPath(), 800, 800);
private Bitmap getBitmapFromGallery(String path, int width, int height) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, width, height);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
Bitmap bitmap = BitmapFactory.decodeFile(path, options);
// if you use image from camera then in some cases it will rotated automatically like it was captured landscape but displays portrait then you have to use method `checkAndRotateBitmap()` which was also given below
// bitmap = checkAndRotateBitmap(bitmap);
return bitmap;
}
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) >= reqHeight
&& (halfWidth / inSampleSize) >= reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
private Bitmap checkAndRotateBitmap(Bitmap bmp) {
try {
ExifInterface ei = new ExifInterface(imgPath);
int orientation = ei.getAttributeInt(ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_UNDEFINED);
Bitmap rotatedBitmap;
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
rotatedBitmap = Helper.rotateImage(bmp, 90);
break;
case ExifInterface.ORIENTATION_ROTATE_180:
rotatedBitmap = Helper.rotateImage(bmp, 180);
break;
case ExifInterface.ORIENTATION_ROTATE_270:
rotatedBitmap = Helper.rotateImage(bmp, 270);
break;
case ExifInterface.ORIENTATION_NORMAL:
default:
rotatedBitmap = bmp;
}
return rotatedBitmap;
} catch (IOException e) {
e.printStackTrace();
return bmp;
}
}
EDIT
有关如何进行的更多信息getBitmapFromGallery()方法有效，你应该看看https://medium.com/android-news/loading-large-bitmaps-efficiently-in-android-66826cd4ad53 https://medium.com/android-news/loading-large-bitmaps-efficiently-in-android-66826cd4ad53
这就是我的全部朋友，现在尝试一种满足您要求的方法，让我知道这是否有效，如果有任何问题，也请帮助我改进我的答案..谢谢！
